CENTRALISED VERSUS ON-SITE ANAEROBIC DIGESTION SYSTEMS FOR FOOD WASTE RECYCLING IN SINGAPORE

Abstract

This paper seeks to compare between implementing a centralised and an on-site anaerobic digestion (AD) system for the recycling of food waste in Singapore. To understand how a centralised system could work in Singapore, the experience with IUT Global, previously Singapore’s largest food waste recycling facility, was tapped upon. For on-site systems, as it is unprecedented in Singapore, we hypothesised a system in a hawker centre setting where the award-winning Flexibuster™ micro AD containerised technology is used to process food waste, supported by a food waste segregation and collection system adapted from the ongoing food waste recycling pilots in two hawker centres in Singapore. Challenges identified with implementing centralised systems included the source segregation of food waste, conflict of interest with licenced waste collectors as well as the market for compost and electricity. For on-site systems, on top of similar issues of source segregation of food waste and the market for products, it was also found that questions of technology availability, operation and maintenance requirements as well as space constraints had to be dealt with too. Upon evaluation, it was determined that the most crucial challenge in implementing a centralised system would be the source segregation of food waste, while for on-site systems, the biggest stumbling block would be space constraints. Also, regardless of it being on-site or centralised, it was found that the underlying foundation required for either system to function in Singapore would be a source segregation law. With that in place, the biggest issue concerning centralised systems would be resolved, but not so for on-site systems. In fact, for on-site systems to be implemented, it may require a renovation of the building, or that it would be incorporated in the development plan of a future building. Hence, when comparing between centralised and on-site food waste recycling systems, it appears that the centralised one would be easier to implement. Furthermore, though one advantage of the micro AD technology in an on-site system is supposed to be its low spatial requirement, it still in effect requires more land area to treat a given unit of food waste as compared to that of a centralised facility. Hence, in the context of Singapore, considering the relative ease of implementation as well as lower unit footprint, it is probably more worthwhile to pursue a centralised food waste recycling system in the country at this point in time. iii Finally, in view of the findings from the paper, it is proposed that one, that a source segregation law be mandated; two, that an accompanying Code of Practice is released to guide food establishments; three, that Singapore establishes proper compost standards to safeguard the market for high-quality compost; four, that in spite of the superior suitability of centralised systems, research interest for on-site AD systems remains; and last, that Singapore keep up with the latest waste technologies and remain open-minded to altering existing systems, especially if the change goes in sync with the notion of circular economy which resource-scarce Singapore ought to ultimately subscribe to.